1. Field of the Invention
The invention relates to an implantable device with a charging current feed arrangement having at least one receiving coil into which energy can be transcutaneously fed electromagnetically via a charging device located outside the body, with an electrochemical battery which can be repeatedly recharged via the charging current feed arrangement, and with a main module supplied by the battery with electric power, the components of the implantable device, with the exception of the receiving coil, being accommodated in a housing arrangement of biocompatible metal and the receiving coil sitting, outside the housing arrangement and being electrically coupled to the other part of the implantable device.
2. Description of Related Art
U.S. Pat. No. 5,279,292 discloses a hearing aid or tinnitus masker in which a main module and a power supply module with a rechargeable electrochemical battery can be accommodated in a common housing, or each can have its own separate housing, the common housing,or the housing of the power supply module also holding the receiving coil into which power can be electromagnetically supplied transcutaneously via the charging device located outside of the body. The implant housing(s) must be hermetically gas-tight. Therefore, for the housing containing the receiving coil, based on transcutaneous charging current feed, use can be made of ceramic materials, for example, Al.sub.2 O.sub.3 or the like. However, ceramic housings are expensive and relatively sensitive to impact. This patent also describes an implantable device with a charging current feed arrangement, in which power is supplied percutaneously to a receiving coil located outside the implant housing; the receiving coil includes a ferrite core which extends through the skin. Any percutaneous arrangement, however, represents a potential source of infection or injury. The presence of an implant becomes disruptively visible from the outside. Nuclear spin tomographic studies of the implant wearer and the like are undesirably precluded by the ferrite core.
U.S. Pat. No. 5,702,431 discloses a transcutaneous recharging system for battery-powered implantable medical devices, especially defibrillators, in which a receiving coil of a charging current feed arrangement is located outside the device housing and is electrically coupled to the implantable device and in which the implantable device is accommodated in a titanium or stainless steel housing.